THEORY OF MACHINES 2022 Question Paper — Government College of Engine…

Instructions

• Attempt five questions in all selecting at least two questions from each Section.
• Each question carries 20 marks.
• Assume missing data, if any.

Questions

Section A

• QQ1. Figure 1 shows a plane mechanism with link lengths given in some unit. If slider A is the driver, then determine whether link CG will rotate or oscillate? Justify your answer. [20 marks]
• QQ2. A pinion having 18 teeth engages with an internal gear having 72 teeth. If the gears have involute profiled teeth with $20^\circ$ pressure angle, module of 4 mm and the addenda on pinion and gear are 8.5 mm and 3.5 mm respectively, find the length of path of contact. [20 marks]
• QQ3. A cam having a lift of 10 mm operates the suction valve of a four stroke SI engine. The least radius of the cam is 20 mm and nose radius is 2.5 mm. The crank angle for the engine when suction valve opens is $4^\circ$ after TDC and it is $50^\circ$ after BDC when the suction valve closes. The crank shaft speed is 2000 rpm. The cam is of circular type with circular nose and flanks. It is integral with cam shaft and operates a flat faced-follower. Estimate (a) the maximum velocity of the valve, (b) the maximum acceleration and retardation of the valve, and (c) the minimum force to be exerted by the spring to overcome inertia of the valve parts which weigh 2 N. [20 marks]
• QQ4. For a spring controlled Hartnell type governor, following data is provided: Mass of the governor ball = 1.80 kg Length of the vertical bell crank lever = 8.75 cm Length of other arm of bell crank lever = 10.0 cm If the speeds corresponding to radii of rotations of 12 cm and 13 cm are 296 and 304 r.p.m. respectively. Find the stiffness of spring. [20 marks]

Section B

• QQ5. An aeroplane makes a complete half circle of 50 metres radius, towards left, when flying at 200 km per hr. The rotary engine and the propeller of the plane has a mass of 400 kg and a radius of gyration of 0.3 m. The engine rotates at 2400 r.p.m. clockwise when viewed from the rear. Find the gyroscopic couple on the aircraft and state its effect on it. [20 marks]
• QQ6. A horizontal steam engine running at 120 r.p.m. has a bore of 250 mm and a stroke of 400 mm. The connecting rod is 0.6 m and mass of the reciprocating parts is 60 kg. When the crank has turned through an angle of $45^\circ$ from the inner dead centre, the steam pressure on the cover end side is 550 $\text{kN/m}^2$ and that on the crank end side is 70 $\text{kN/m}^2$. Considering the diameter of the piston rod equal to 50 mm, determine: (a) Turning moment on the crank shaft, (b) Thrust on the bearings, and (c) Acceleration of the flywheel, if the power of the engine is 20 kW, mass of the flywheel 60 kg and radius of gyration 0.6 m. [20 marks]
• QQ7. A rotating shaft carries four unbalanced masses 20, 15, 18 and 10 kg at radii 50, 60, 70 and 65mm, respectively. The $2^\text{nd}$, $3^\text{rd}$ and $4^\text{th}$ masses revolve in planes 80, 150 and 300 mm respectively measured from the plane of the first mass and are angularly located at $60^\circ$, $130^\circ$ and $270^\circ$ respectively measured anti-clockwise from the first mass looking from this mass end of the shaft. The shaft is dynamically balanced by two masses, both located at 50 mm radii and revolving in planes mid-way between those of first and second masses and midway between those of $3^\text{rd}$ and $4^\text{th}$ masses. Determine the magnitudes of the masses and their respective angular position. [20 marks]
• QQ8. A four-bar mechanism shown in Fig.2 is subjected to torques $T_3 = 50\text{ Nm}$ and $T_4 = 60\text{ Nm}$. The dimensions of the various links are: [20 marks]

Related pages

• THEORY OF MACHINES syllabus
• All THEORY OF MACHINES papers from 2022

Other years

• THEORY OF MACHINES 2018 question paper — end-term